This invention concerns a watertight watch with a piezo electric buzzer mechanism and a safety arrangement in order to prevent a lasting deformation or a destruction of a diaphragm in case of too great a load through pressure or thrust. The watch is preferably of the type whose housing bottom has outlet openings for transmitting sound, on the inside of which housing bottom the piezo element has been disposed in a manner functioning additionally as a sealing element.
Through German Pat. No. 2,215,768, especially through FIG. 7 thereof, a watch with an electronic alarm has been known which comprises the above-recited features. In such a watch, a carrier plate has been provided as a safety element, the plate being disposed at a slight distance from the diaphragm. The plate is intended to prevent any unduly high pressure acting on the diaphragm from deforming the diaphragm excessively or damaging it. Such a carrier plate is disposed in close proximity to the diaphragm. The plate has, however, the disadvantage that it takes up too much space for one thing, and for another, that in case of too great an amplitude of the axial oscillation movement of the diaphragm and piezo element, the latter can be damaged or destroyed as a result of too frequently striking against the carrier plate.
Therefore, it is an object of the invention to create in connection with a watertight watch having a diaphragm functioning also as a sealing element, an economical and easily installable device which protects the diaphragm against lasting deformation or destruction. Such protection can, for example, be effective during a check for watertightness by forces which are multiple times the usual pressure. Moreover, it is another object that an effective limitation of the amplitude of diaphragm movement be achieved in both directions of oscillation.